The Assignees of the present application manufacture a machine as shown in a number of the following patents which disclose machines of this general type and features which relate to such machines:
U.S. Pat. No. 5,895,345Issued Apr. 20, 1999U.S. Pat. No. 5,222,933Issued Dec. 13, 1994U.S. Pat. No. 5,338,284Issued Aug. 16, 1994U.S. Pat. No. 5,586,965Issued Dec. 24, 1996U.S. Pat. No. 5,601,523Issued Feb. 11, 1997U.S. Pat. No. 5,601,524Issued Feb. 11, 1997U.S. Pat. No. 4,983,156Issued January 1991.U.S. Pat. No. 4,846,781Issued July 1989.U.S. Pat. No. 4,776,833Issued October 1988.U.S. Pat. No. 4,608,040Issued Aug. 26, 1986.
The disclosure of the above patents all filed by Benjamin Knelson is incorporated herein by reference.
In addition to the above patents of the present inventor, the following patents by other inventors show machines and features of a similar nature:
McAllisterU.S. Pat. No. 4,824,431Apr. 25, 1989McAllisterU.S. Pat. No. 5,462,513Dec. 31, 1995McAllisterPCT/WO 99/661161Dec. 2, 1999McAllisterPCT/WO 96/37307Nov. 28, 1996ClassiconUK 2,133,722Aug. 1, 1984BurnellU.S. Pat. No. 4,981,219Jan. 1, 1991MacNicolAustralia 1,748,7/34May 8, 1934Australia 22055/35Apr. 2, 1935MacIsaacU.S. Pat. No. 1,882,389Oct. 11, 1932LoisonU.S. Pat. No. 3,823,869Jul. 16, 1974TelleDT 1,632,324Oct. 29, 1970
The McAllister patents show a rudimentary impeller at the bottom of the bowl onto which the feed material is deposited with the intention of accelerating the feed material as it passes onto the wall of the bowl for separation. The 431 patent shows the impeller in most detail but this comprises merely a bottom plate supported on legs over a bottom drain opening of the bowl on which is mounted a plurality of radial vanes.
The MacIsaac patent discloses a bowl which is filled with pulp and rotated to extract water and includes fins on an impeller arrangement at the bottom of the bowl.
One problem which can occur in the feeding of material onto the bowl wall is that some of the material can collect into a concentrated stream as a “snake” which thus interferes with what should otherwise be a smooth layer over the bowl wall for proper separation to occur. Thus the “snake” contains unprocessed slurry which by-passes the centrifugal separation effect of the rings leading to loss of concentrate.